Field of the Invention
The present invention relates to an ophthalmologic apparatus that can be used in ophthalmologic diagnosis and treatment, and relates to a method for controlling the ophthalmologic apparatus.
Description of the Related Art
Eye examinations have been widely performed for the purpose of early diagnosis and treatment of a lifestyle related disease or a disease having the high possibility of leading the cause of blindness. A scanning laser ophthalmoscope (SLO) is an ophthalmologic apparatus that is operable based on the principle of a confocal laser microscope. The SLO apparatus can perform raster scanning of an eye fundus with laser (i.e., measurement light) and can acquire high-resolution and high-speed plane images based on the intensity of return light. The plane images acquired by the SLO apparatus are hereinafter referred to as SLO images.
A recent SLO apparatus is configured to use measurement light having a larger beam diameter, so that a captured SLO image of a retina is excellent in horizontal resolution. However, if the beam diameter of the measurement light becomes larger, a problem will occur in acquiring an SLO image of a retina. For example, the acquired SLO image will be insufficient in S/N ratio and/or resolution due to aberration of an examinee's eye. To solve the above-mentioned problem, an adaptive optics SLO apparatus can be configured to include a wavefront sensor capable of measuring the aberration of an examinee's eye in real time and a wavefront correcting device capable of correcting the aberration of measurement light or return light occurring in the examinee's eye. The adaptive optics SLO apparatus having the above-mentioned arrangement can acquire SLO images excellent in horizontal resolution (i.e., high magnification images).
The above-mentioned high magnification images can be acquired as a moving image and can be used, for example, to observe blood flow dynamics noninvasively. In this case, it is feasible to extract a retina blood vessel from each frame and measure the moving speed of a blood corpuscle in the capillary. Further, to evaluate the relevancy to the visual function using high magnification images, it is feasible to detect visual cells P and measure the density distribution and/or the arrangement of the visual cells P. FIG. 6B illustrates an example of the high magnification image, in which visual cells P, a low-luminance region Q representing the position of a capillary, and a high-luminance region W representing the position of a white blood cell can be observed.
In this case, in a case where high magnification images are used to observe the visual cells P or measure the distribution of the visual cells P, the focus position is set adjacently to an outer layer of a retina (see B5 in FIG. 6A) to capture a high magnification image as illustrated in FIG. 6B. On the other hand, a retina blood vessel and branched capillaries are extensively distributed in an inner layer of a retina (see B2 to B4 in FIG. 6A). In this case, an imaging target region to be set in capturing an image of an examinee's eye tends to become larger in comparison with the angle of view of the high magnification image. For example, the above-mentioned relationship will be recognized when an imaging target is a visual cell missing region extending in a wide range or a parafovea region (i.e., a favorite site of an initial capillary lesion). In view of the foregoing, as discussed in Japanese Patent Application Laid-Open No. 2012-213513, there is a conventionally known technique capable of displaying an image composite (montaged images) composed of a plurality of high magnification images captured at different photographing positions.
Further, as discussed in Japanese Patent Application Laid-Open No. 2013-169309, there is a conventionally known technique capable of identifying an exceptional frame having a larger influence (e.g., involuntary eye movement) in a high-magnification moving image captured at a specific photographing position and displaying all frames of the high-magnification moving image except for the determined exceptional frames.